Procedures commonly used in forming a press-fitted structural joint between two elements usually involve a number of pressing operations prior to the forming of the structural joint. This additional handling of the elements before they are joined may result in added manufacturing costs.
The method of forming a structural joint according to this invention overcomes this problem by forming a simply constructed joint which securely retains two elements in connected relationship. The elements to be joined are characterized in that the first element has at least one flange extending from a face thereof where each flange has an outer end. The second element has at least one elongate groove which is substantially arcuate in cross-section and is provided on a face thereof, each of the grooves having opposed edges which define an elongate opening of a dimension to permit entry of the flange into the groove. The outer end of each of the flanges is placed into the elongate opening of a respective groove, then a sufficient external force is applied to at least one of the first and second elements to cause relative movement between the elements so as to decrease the distance between the opposing faces thereof. As the distance between the opposing faces is decreasing, each flange is deformed within the respective groove to form at least a portion of a coil therein. Once the flange has been deformed within the groove to form the desired degree of coiling within the groove so that the width of the coil is greater than the width of the elongate opening, the external force is removed. This results in a structural joint between the two elements where the flange of the first element is coiled within the groove of the second element to retain the elements in connected relationship.
This method may be adapted to join any two desired pieces of material or to join the edges of a blank piece of material thereby forming a hollow cylinder. This method has many fields of application such as being used to join a ladder rung to a ladder rail. Another is in the joining of at least two elements together, the degree of coiling the flange within the groove being varied along the length of the structural joint to form a taper between opposing faces of the elements being joined. The taper along the joint may be useful in forming tapered columns and the like.